Physical Properties of Aromatic Hydrocarbons. II. Solidification Behavior of 1,3,5-Tri-α-Naphthylbenzene

Magill, J. H.; Plazek, D. J.

doi:10.1063/1.1840448

Cited by 137 publications

(109 citation statements)

References 27 publications

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“…This leads to a maximum in the V-∆T relation. This was experimentally observed in a great variety of non-metallic glass-forming systems, such as o-terphenyl [66], tri-α-naphthylbenzene [67], Li 2 O-2SiO 2 [68], and MgO-CaO-2SiO 2 [69]. However, thus far, there is only one work that reports a maximum in the V-∆T relation measured for the Cu 50 Zr 50 glass-forming alloy [32].…”

Section: Dendrite Growth In Undercooled Glass-forming Cu 50 Zr 50 Alloymentioning

confidence: 99%

Non-Equilibrium Solidification of Undercooled Metallic Melts

Herlach

2014

Metals

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Abstract:If a liquid is undercooled below its equilibrium melting temperature an excess Gibbs free energy is created. This gives access to solidification of metastable solids under non-equilibrium conditions. In the present work, techniques of containerless processing are applied. Electromagnetic and electrostatic levitation enable to freely suspend a liquid drop of a few millimeters in diameter. Heterogeneous nucleation on container walls is completely avoided leading to large undercoolings. The freely suspended drop is accessible for direct observation of rapid solidification under conditions far away from equilibrium by applying proper diagnostic means. Nucleation of metastable crystalline phases is monitored by X-ray diffraction using synchrotron radiation during non-equilibrium solidification. While nucleation preselects the crystallographic phase, subsequent crystal growth controls the microstructure evolution. Metastable microstructures are obtained from deeply undercooled melts as supersaturated solid solutions, disordered superlattice structures of intermetallics. Nucleation and crystal growth take place by heat and mass transport. Comparative experiments in reduced gravity allow for investigations on how forced convection can be used to alter the transport processes and design materials by using undercooling and convection as process parameters.

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Section: Dendrite Growth In Undercooled Glass-forming Cu 50 Zr 50 Alloymentioning

confidence: 99%

Non-Equilibrium Solidification of Undercooled Metallic Melts

Herlach

2014

Metals

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“…influence spherulitic growth morphology. Multistage heat treatments on polymeric substances have demonstrated that that both the local growth morphology and growth rate depend on the temperature, but are independent of previous thermal history [1,10,62]. For example, cycling between two temperatures reversibly switches between faceted and spherulitic growth morphologies both in experiment [1,10] and simulation [ Figs.…”

Section: Multi-step Heat Treatmentsmentioning

confidence: 99%

“…While there is no generally accepted theory of spherulite crystallization, a number of phenomenological models and necessary physical conditions for this process have been suggested [1,[8][9][10]22]. The most prevalent conception of their origin is the qualitative model of Keith and Padden [13], in which the presence of static heterogeneities (impurities or molecular defects and mass polydispersity in polymeric materials) lead to a rejection of these components from the growth front to form channels similar to those found in eutectics.…”

Section: Introductionmentioning

confidence: 99%

“…They are observed in a wide range of metallurgical alloys, in pure Se [2,3], in oxide and metallic glasses [4,5], mineral aggregates and volcanic rocks [6,7], polymers [1,8], liquid crystals [9], simple organic liquids [10], and diverse biological molecules [11]. Many everyday materials, ranging from plastic grocery bags to airplane wings and cast iron supporting beams for highway bridges, are fabricated by freezing liquids into polycrystalline solids containing these structures.…”

Section: Introductionmentioning

confidence: 99%

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Growth and form of spherulites

et al. 2005

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Many structural materials (metal alloys, polymers, minerals, etc.) are formed by quenching liquids into crystalline solids. This highly non-equilibrium process often leads to polycrystalline growth patterns that are broadly termed 'spherulites' because of their large-scale average spherical shape. Despite the prevalence and practical importance of spherulite formation, only rather qualitative concepts of this phenomenon exist. The present work explains the growth and form of these fundamental condensed matter structures on the basis of a unified field theoretic approach. Our phase field model is the first to incorporate the essential ingredients for this type crystal growth: anisotropies in both the surface energy and interface mobilities that are responsible for needle-like growth, trapping of local orientational order due to either static heterogeneities (impurities) or dynamic heterogeneities in highly supercooled liquids, and a preferred relative grain orientation induced by a misorientation-dependent grain boundary energy. Our calculations indicate that the diversity of spherulite growth forms arises from a competition between the ordering effect of discrete local crystallographic symmetries and the randomization of the local crystallographic orientation that accompanies crystal grain nucleation at the growth front (growth front nucleation or GFN). The large-scale isotropy of spherulitic growth arises from the predominance of GFN.

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“…This growth form is most familiar in polymers, where spherulites are the typical crystallization mode 1{6] (although not all polymer solids are crystalline). However, spherulites have a l s o been investigated in materials as dissimilar as elemental selenium 7{9], low molecular-weight systems with polymeric impurities 10], organic materials 11,12], biological molecules 2], mineral aggregates 13{15], and liquid crystals 16{18]. The presence of spherulites in uences the mechanical properties of commercial materials.…”

Section: Introductionmentioning

confidence: 99%